Present embodiments relate generally to gas turbine engines. More particularly, but not by way of limitation, present embodiments relate to apparatuses and methods for increasing convective heat transfer to improve reactance of a process sensor.
In turbine engines, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gas which flow downstream through turbine stages. These turbine stages extract energy from the combustion gas. A high pressure turbine includes a first stage nozzle and a rotor assembly including a disk and a plurality of turbine blades. The high pressure turbine first receives the hot combustion gas from the combustor and includes a first stage stator nozzle that directs the combustion gas downstream through a row of high pressure turbine rotor blades extending radially outwardly from a first rotor disk. In a two stage turbine, a second stage stator nozzle is positioned downstream of the first stage blades followed in turn by a row of second stage turbine blades extending radially outwardly from a second rotor disk. The stator nozzles direct the hot combustion gas in a manner to maximize extraction at the adjacent downstream turbine blades.
The first and second rotor disks are joined to the compressor by a corresponding rotor shaft for powering the compressor during operation. These are typically referred to as the high pressure turbine. The turbine engine may include a number of stages of static airfoils, commonly referred to as vanes, interspaced in the engine axial direction between rotating airfoils commonly referred to as blades. A multi-stage low pressure turbine follows the two stage high pressure turbine and is typically joined by a second shaft to a fan disposed upstream from the compressor in a typical turbo fan aircraft engine configuration for powering an aircraft in flight.
As the combustion gas flows downstream through the turbine stages, energy is extracted therefrom and the pressure of the combustion gas is reduced. The combustion gas is used to power the compressor as well as a turbine output shaft for power and marine use or provide thrust in aviation usage. In this manner, fuel energy is converted to mechanical energy of the rotating shaft to power the compressor and supply compressed air needed to continue the process.
Process sensors are utilized by airplane avionics to control various operating conditions. For example, the temperature along with other characteristics are used to determine mass flow of the air entering the turbine engine. Such mass flow may be utilized by the engine control logic or avionics to determine fuel input to the engine as well. Therefore, it is desirable to improve the accuracy of the mass flow calculations in the engine control logic to improve engine fuel savings as well as determine the life spans of critical engine components.
One issue with process sensors is response time or reactance. For example, as related to temperature, air entering the jet engines can change temperature very rapidly. However, many air temperature sensors have low reactance, and accordingly the temperature sensor may not detect the temperature change fast enough. Thus improvement of the response or reactance of the air temperature sensor may identify hot and cold streaks faster which allow the engine control logic to adjust appropriately and in a timely manner.
As may be seen from the foregoing, there is a need to optimize convective response characteristics of process sensors. Additionally, there is a need to improve reactance of the process sensor so that engine efficiency and performance of the turbine engine may be improved as well. It would be desirable to improve performance of the gas turbine engine at various operating conditions.